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        <h1>SpringBoot自动配置原理 - 学习卡片</h1>
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      <div class="card">
        <div class="card-face card-front">
          <div class="card-category">理论</div>
          <div class="card-question">SpringBoot自动配置的核心理念是什么？</div>
          <div class="card-footer">点击卡片查看答案</div>
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          <div class="card-category">理论</div>
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            <div class="card-answer">SpringBoot自动配置基于“约定优于配置”（Convention over Configuration）的理念。它能够根据项目中使用的依赖和上下文环境，自动加载和初始化所需的Spring Bean，从而极大地简化配置过程，让开发者无需手动编写复杂的配置代码，专注于业务逻辑。</div>
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          <div class="card-source">来源: 自动配置概述</div>
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          <div class="card-category">机制</div>
          <div class="card-question">@EnableAutoConfiguration注解是如何找到并加载自动配置类的？</div>
          <div class="card-footer">点击卡片查看答案</div>
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          <div class="card-category">机制</div>
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            <div class="card-answer">当@EnableAutoConfiguration被激活时，它会借助SpringFactoriesLoader工具类扫描所有类路径下的`META-INF/spring.factories`文件。通过读取文件中以`org.springframework.boot.autoconfigure.EnableAutoConfiguration`为键的配置项，获取到所有自动配置类的全限定名列表，并加载它们。</div>
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          <div class="card-source">来源: @EnableAutoConfiguration注解</div>
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        <div class="card-face card-front">
          <div class="card-category">技术</div>
          <div class="card-question">在自动配置中，@ConditionalOnMissingBean注解通常用于什么场景？</div>
          <div class="card-footer">点击卡片查看答案</div>
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          <div class="card-category">技术</div>
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            <div class="card-answer">@ConditionalOnMissingBean注解用于确保只有在Spring容器中不存在指定类型的Bean时，才会创建并注册一个默认的Bean。这为开发者提供了灵活性，允许他们通过定义自己的同类型Bean来覆盖SpringBoot提供的默认配置。</div>
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          <div class="card-source">来源: @Configuration 和 @Bean 与自动配置的结合</div>
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    <div class="card-container" onclick="this.classList.toggle('flipped');">
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        <div class="card-face card-front">
          <div class="card-category">组件</div>
          <div class="card-question">SpringFactoriesLoader在SpringBoot自动配置中扮演了什么关键角色？</div>
          <div class="card-footer">点击卡片查看答案</div>
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          <div class="card-category">组件</div>
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            <div class="card-answer">SpringFactoriesLoader是SpringBoot自动配置机制的核心实现依赖。它是一个工具类，负责从类路径下所有`META-INF/spring.factories`文件中动态加载指定的组件。在自动配置中，它主要用来发现并加载所有标记为自动配置的类，是实现“按需加载”和模块化配置的基础。</div>
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          <div class="card-source">来源: SpringFactoriesLoader 加载自动配置</div>
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        <div class="card-face card-front">
          <div class="card-category">特性</div>
          <div class="card-question">请列举并解释SpringBoot自动配置的三个主要特点。</div>
          <div class="card-footer">点击卡片查看答案</div>
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          <div class="card-category">特性</div>
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            <div class="card-answer">1. 按需加载：只加载应用程序实际需要的组件和功能。<br>2. 条件化配置：基于上下文环境（如类路径、属性配置、已存在的Bean等）来决定是否加载某些Bean。<br>3. 无侵入性：允许开发者通过显式配置来覆盖自动配置的默认行为，不会强制使用。</div>
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          <div class="card-source">来源: 自动配置概述</div>
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          <div class="card-category">机制</div>
          <div class="card-question">描述一下SpringBoot自动配置生效的完整流程。</div>
          <div class="card-footer">点击卡片查看答案</div>
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          <div class="card-category">机制</div>
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            <div class="card-answer">1. 应用启动时，@SpringBootApplication或@EnableAutoConfiguration激活自动配置过程。<br>2. SpringFactoriesLoader扫描所有依赖中的`META-INF/spring.factories`文件，获取自动配置类列表。<br>3. 对每个自动配置类，评估其上的@Conditional系列条件注解。<br>4. 只有满足条件的配置类才会被激活，其内部定义的@Bean会被创建并注册到Spring容器中。<br>5. 用户的自定义配置会优先于自动配置，实现覆盖。</div>
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          <div class="card-source">来源: 自动配置的生效过程</div>
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          <div class="card-category">技术</div>
          <div class="card-question">除了@ConditionalOnClass和@ConditionalOnBean，请再列举两种常用的条件注解并说明其作用。</div>
          <div class="card-footer">点击卡片查看答案</div>
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          <div class="card-category">技术</div>
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            <div class="card-answer">1. `@ConditionalOnProperty`：根据配置文件（如application.properties）中的某个属性值来决定是否启用配置。例如，只有当`app.feature.enabled`属性值为`true`时才激活。<br>2. `@ConditionalOnWebApplication`：指示配置仅在Web应用程序上下文中才会启用，常用于与Web相关的自动配置。</div>
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          <div class="card-source">来源: 自动配置的触发条件</div>
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    <div class="card-container" onclick="this.classList.toggle('flipped');">
      <div class="card">
        <div class="card-face card-front">
          <div class="card-category">理论</div>
          <div class="card-question">在SpringBoot中，@Configuration和@Bean注解如何与自动配置机制协同工作？</div>
          <div class="card-footer">点击卡片查看答案</div>
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        <div class="card-face card-back">
          <div class="card-category">理论</div>
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            <div class="card-answer">自动配置类本身通常被`@Configuration`注解标记，表明它是一个配置源。在这些配置类内部，使用`@Bean`方法来定义和创建默认的Bean实例。这种组合使得SpringBoot能够模块化地提供默认配置，同时通过`@Conditional`注解控制这些Bean是否被加载，最终实现了默认配置与用户自定义配置的无缝融合。</div>
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          <div class="card-source">来源: @Configuration 和 @Bean 与自动配置的结合</div>
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          <div class="card-category">技术</div>
          <div class="card-question">如果想禁用某个特定的自动配置类，例如数据源自动配置，有哪两种主要方法？</div>
          <div class="card-footer">点击卡片查看答案</div>
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          <div class="card-category">技术</div>
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            <div class="card-answer">有两种主要方法可以禁用特定的自动配置类：<br>1. 在启动类上使用`@EnableAutoConfiguration`的`exclude`属性，例如：`@EnableAutoConfiguration(exclude = {DataSourceAutoConfiguration.class})`。<br>2. 在配置文件（如application.properties）中通过`spring.autoconfigure.exclude`属性指定要排除的类的全名，例如：`spring.autoconfigure.exclude=org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration`。</div>
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          <div class="card-source">来源: @EnableAutoConfiguration注解</div>
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